Compile code that gets linked with libc by adding -fhosted.

Compile code that gets linked with libc by adding -fhosted.

The use of -fno-builtin interfers with -Wformat: no format warnings will
be given when both options are present. Because -fno-builtin means: when
you encounter a function that has the same name as a built-in function,
forget everything you know about that function.
That includes functions attributes. And without __attribute__((format...))
there will be no -Wformat warnings.

The fix is to append -fhosted when compiling something that gets linked
with libc. As command line options are processed left to right adding
-fhosted at the end overrides any earlier -fno-builtin option.

Fix compiler warnings.

Add some ugly ifdeffery to drd/drd_intercepts.c. I could not figure out how
to rewrite the offensive printf to avoid testcase breakage.